The problem involved in treatment for disposal of municipal waste concerns the "ultimate disposal" of the noxious material therein.
The ultimate disposal of liquidous wastes, especially municipal waste or (sewage) is a perplexing, expensive problem.
The present partial solutions to the problem include the primary treatment of such wastes, which involve merely the removal of the gross contaminants; secondary treatment involving a partial digestion of the contaminating solids, using air or even oxygen sparging to both promote the metabolic process of aerobic microbes while suppressing the growth and/or reproduction of anaerobic species, such as the clostridii, which produce very toxic metabolic by-products. Present methods may involve expensive filtration steps, and sometimes sterilization, and these processes constitute the total of the treatment given municipal waste by the vast majority of municipal waste-treatment plants in existence, or even contemplated. The product of such plants may consist of 96-99.5% water, but it is a gray suspension, susceptible to conversion to septic material in about 20 minutes, and is not only non-palatable but repugnant in appearance and odor.
These conventional processes merely, for the most part, convert one form of nuisance into another form, and the problem of "ultimate disposal" in some harmless, or preferably useful, form largely remains unsolved.
The conventional processes of disposal of municipal waste, i.e., sewage, treatment, specifically those other than mere burial, usually involve the oxidation of the organic constituents therein, whether by incineration or wet-oxidation methods, both direct and biological, are a fearful waste both of the compounds therein and of the fuel required in all cases. The organic constituents were formed by consumption of the energy required for their synthesis, by either sunlight or man's expenditure of energy thereupon; e.g., that energy used in the manufacture of synthetic fertilizers, and the waste incurred by merely burning them to get rid of them is obvious. Also, the fuel-fired drying and incineration consumes fuels in such a way that no useful purpose is served in terms of recovery of such energy requirements and the energy stored in the components being destroyed.
This wastage is best illustrated by the fate of the nitrogenous compounds in municipal waste. These compounds are the main source of nuisance in such wastes, but the synthesis thereof required extensive amounts of energy, particularly when they were derived from synthetic fertilizers. The incineration of such compounds converts them almost exclusively to free nitrogen gas; the re-fixation of the nitrogen gas for conversion to nitrogen-containing fertilizers requires a further expenditure of energy. This re-fixed nitrogen absurdly enough is often synthesized to the same kinds of nitrogenous compounds which are originally present in the municipal waste; thus certain of the conventional procedures constitute a cycle, but the net result is the waste of the energy required for continual re-formation of nitrogenous compounds from free atmospheric nitrogen.
It is true that certain conventional municipal waste disposal processes produce nitrogenous fertilizer; however, these materials are ordinarily non-sterile. It is a historical fact that civilizations using natural animal waste fertilizers, especially those which use human waste, have endemic dysentery as a continual problem.
The use of fossil fuels for production of various forms of energy to continually destroy and reform such nitrogenous compounds drains exhaustible energy sources.
It would be extremely desirable to use compounds produced every day by the sun as a source of fuels, and especially liquid (fluid) fuels, which are more easily transported and stored than other fuel forms.
Thus, there remain the several problems of practical concentration, sterility, and ultimate disposal of municipal waste, plus the desirability of recovery of the energy represented by the composition thereof.
In the process of this invention the solid organic portion of the impurities of Municipal waste water is concentrated, saccharified to a fermentable state by heatings, then fermented, and the combustible fraction therein separated, e.g. by distillation; thus producing liquid fuel such as that useable in production of energy, and also residue suitable for animal feed, and purified water.